The SD1076 transistor dates from the late 1970s. A data sheet has never been posted online where I could find it.
But here is a catalog list of some sort. Says it's rated for 70 Watts output, with 13.5 db power gain. That's a gain factor of about twenty to one. Should suggest that a single transistor needs about 3.5 Watts drive to get 70 Watts out.
Does say it's meant for a 12-Volt power supply. Might check inside this one to see if it's "cheating" with a high power supply voltage.
This thing is really old. If it has survived this long with original transistors, that would really be some performance record.
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